The present invention relates to multiple source optical scanners and more specifically to a backup method for a multiple source optical scanner.
In the related Application cited above, a multiple source optical scanner is disclosed. A first embodiment of the optical scanner includes a plurality of scanning light sources of different wavelengths, collimating and focusing optics for producing a beam for each source, reflecting optics for aligning each beam in a predetermined direction, a collector for collecting light reflected from a bar code label to be scanned, filter optics for separating the different wavelengths of light, and processing circuitry having a plurality of processing channels for converting the reflected light of each wavelength into electrical signals based upon the intensities of the reflected light. The first embodiment may also include a mirrored spinner and a plurality of pattern mirrors.
A second embodiment of the optical scanner includes a plurality of scanning light sources of the same wavelength, collimating and focusing optics for producing a beam for each source, reflecting optics for aligning each beam in a predetermined direction, a collector for collecting light reflected from a bar code label to be scanned, and processing circuitry having a single processing channel for converting the reflected light into electrical signals based upon the intensities of the reflected light. The scanner additionally includes modulation and control circuitry, which turns the sources off and on in sequence. The second embodiment may also include a mirrored spinner and a plurality of pattern mirrors.
While the multiple source optical scanner works well, it is difficult for an operator to determine when one of the sources has failed. In such a state, the performance of the multiple source optical scanner is reduced.
Therefore, it would be desirable to provide a backup method for a multiple source optical scanner which detects a malfunctioning source and alerts an operator. In the case of a scanner having multiple full-time channels, it would be desirable to remove power from the failed source, and to disregard the signal from the channel of the failed source. In the case of a scanner having non-simultaneously operating sources, it would be desirable to place the operating sources in a full-time mode of operation.